Design and Synthesis of Reusable Nanoparticles for Reversible Chemisorption of Hexavalent Chromium Anions from Aqueous Media and Catalysis

Table 1

Test results of 0.4 g Fe₃O₄@SiO₂@LEuH@PW₁₀ adsorbent with different chromate concentrations in both tap water and wastewater at 25°C for 1 hour at pH = 6 for tap water and pH = 4.4 for wastewater.

Test material	Volume (ml)	Initial CrO4^2− (ppm)	Final CrO4^2− (ppm)	Adsorbent reuse
Tap water	100	2	ND	ND
	200	2	ND	ND
	300	2	ND	ND
	500	2	ND	ND
Wastewater	100	2	ND	ND
	200	2	ND	ND
	300	2	ND	ND
	500	2	ND	ND
Tap water^†	100	100	ND	ND
	200	100	ND	ND
	300	100	ND	ND
	500	100	ND	ND
Wastewater^†	100	100	ND	ND
	200	100	ND	ND
	300	100	ND	ND
	500	100	ND	ND

Note. Below detection limit (ND) was 0.007 ppm. Adsorbent reused ten times giving similar results; ^†4.0 g of adsorbent used.